de Vries et al.
(1998b,
1998c)
present the results of a study of the spectral energy distribution
across the R, J, H, and K bands of samples
of GPS, CSS, and extended 3CR radio galaxies. They find that GPS, CSS,
and 3CR sources have similar broadband spectra in the near-IR,
consistent with them having similar stellar populations and AGNs
(r - K colors presented by
Snellen et al. 1996a
are also consistent with this). The distribution of the ratio of nuclear
to extended light at K band in all three samples is comparable -
consistent with only a few GPS or CSS or 3CR galaxies being "red
quasars." The sources that are red quasars are likely to be obscured by
material in the host galaxy rather than an intervening galaxy.

de Vries et al. find the R - K spectral energy
distribution (SED) is best-fitted with a metallicity that is consistent
with solar and fairly old stellar populations (older than 5 Gyr)
implying redshift of formation in the range 5-10 depending on the
cosmology. de Vries et al. also find an extra near-IR component is
needed that can be modeled by emission from dust at a temperature of ~
1000 K. If this is the correct interpretation, this may be produced by
circumnuclear material heated by the AGN, perhaps in the putative
obscuring torus.